About Root Shield.
When it first came out about 10 years ago there was a person at the message site where I was at that time who e-mailed the company that produced it and a woman scientist there e-mailed back and said that it had not been tested against Fusarium and it was developed to help prevent root rot for commercial large scale flower growers.
And if you look at a Google search you'll see that the majoirty of the links are directed against using it in that manner.
About Fusarium.
There are three races and no cross immunity and most folks have no idea which races or races they're dealing with although race three is the least common, to date. Whatever the race or races the fungi are not evenly dispersed in a planting area so some varieties will do OK and some will not.
And since the symptoms for Fusarium and Verticillium are quite similar it's often hard to tell which of the two, or both, are a problem.
The genes that give tolerance, not resistance, for the three races were isolated and used in the construction of many hybrid varieties, and not for the home grower but for the large scale farmer and that's b/c with just a week or more growth, which is all that those genes can provide, it helps the farmer b'c that extra time can result in higher Brix readings which is how they determine when to start harvesting.
I can check this out but I seem to remember that the genes for Fusarium tolerance are from one of the species, so it would not be all that common to have many of our garden tomatoes have tolerance to it, depending on their genetic backgrounds.
Also, infection is dose dependent so that's why challenge testing is done with a known amount of Fusarium and controls of known susceptibles and known tolerant varieties before any hybrid can have that F or FF or FFF next to their name.
I don't have to contend with Fusarium where I live but I sure do have lots of tomato friends who do, whether it's from about NC down to FL, then along the Gulf Coast states and then up into CA.
Races 1 and 2 are most common and are multi-genic meaning that mroe than one gene participates in tolerance to race 1 and the same for race 2. The probability that an OP heirloom would have somehow inherited the maxi,um number of genes for race 1 or 2 I think would be very low.
Fusarium CAN be spread via airborne transmission. Which was not news to Craig L in NC who has had a real problem with Fusarium.
Hope the above helps at least somewhat.
And pockets of it do appear here in the north and sometimes it's due to purchased plants whose roots are colonized with it as transplants that are shipped to areas where it's new. But since Fusarium is one of those soilborne diseases that can't overwinter where the ground freezes deeply, it usually doesn't become a permanent problem.
__________________
Carolyn
|